What controls the menstrual cycle?
Your hormones control your menstrual cycle. During each cycle, your brain’s hypothalamus and pituitary gland send hormone signals back and forth with your ovaries. These signals get the ovaries and uterus ready for a pregnancy. The hormones estrogen and progesterone play the biggest roles in how the uterus changes during each cycle. • Estrogen builds up the lining of the uterus. • Progesterone increases after an ovary releases an egg (ovulation) at the middle of the cycle. This helps the estrogen keep the lining thick and ready for a fertilized egg. • A drop in progesterone (along with estrogen) causes the lining to break down. This is when your period starts. A change in hormone levels can affect your cycle or fertility. For example, teens tend to have low or changing progesterone levels. This is also true for women close to menopause. That is why teens and women in their 40s may have heavy menstrual bleeding and cycles that change in length. Other things can change your cycle. They i
